Electrically heated fan-heater



July 12, 1949. M. MORRISON 2,475,910

ELECTRICALLY HEATED FAN-HEATER Original Filed Nov. 27, 1943 INVENTQRPatented July 12, 1949 UNITED STATES PATENT. OFFICE '7 Claims. 1. Thepresent invention relates to ventilating and heatihgart, .relatesin.particular to such an by electrical means, .andrelates specifically toelec-. trical heating unitsprovidedwith electric fans.--

This. application is .a division of application SerialflNo'.511,957,.filed.November..27, 1943,. now.

abandoned.

Among the objects of the inventionrarez-to. provide anelectricallyheatedfan-heater which may be used to circulate/cool air in .warmweatherand to..circulate.-warm.airin cool...weather; to provide.-

in .an 1 electrically. heated. fan-heater. .a structure which permitsoptional focusing of theair circulated so that thecirculated air maybe-directed...

to a restricted location, or itmay be spread out, bysimple manualadjustmentof the device duringl operation, and 'to. provide, anelectrically,

heated fan-heater structure whichis comparatively noiseless in operationso that. it may be used in places .where noise is objectionable, such.as in'ithe presence of. sleeping ,persons, hospital patients andundersimilar conditions.

In the prior .art, .portable electric ventilating fans have beensupplied with screw-type air-propellers revolving in free air. .These.screw-type propellers have large windage losses, considerableradialcomponentof air propulsion, and operating inzopen air havethe,.property of creating large eddy..currents .in the immediatevicinity of the propeller and confiningra. considerable amount of the.air circulation to the general neighborhood of the fan itself insteadofcirculating all the air about the roomunderventilation.

In addition to the low operatingefliciency of these screw-type.air-propellers, they have a high;

moment of inertia which calls for considerable accelerating torque. tobring the propeller up to operating speed and which torque is notrequired afternperating speed is. attained. This combina-.

tion .of" useless power requirements necessitates a the absence of them-In addition, the metallic-bladed screw-type airpropeller produces aconsiderable noise which is.

distasteful. to a large portion of the users of.portable ventilating.electric fans.

In the present invention, a high efiiciency radial.

flow turbine type of. air blower is employed which is known to operateata high'efficiency and is practically noiseless in operation...

In some embodiments'of this invention a screwtype air-propeller may. be.used in. cooperation with the radial flowrotor, if and when desired.

Further, in .the present invention withsuc-h a type of air-impeller; a:deflecting ,surface. is used 40 larger motor than would have to beemployed in.

in which .the column of theair-flow may be con-,.

verged or diverged, as desired under the circum:

stances, .and any. adjustment, between ,conver-- genceof the airrfiowand divergence thereof, may

be. made.manually while the rotor is in operation. Further, the internalair space of such a rotor. ask-employed. in. the present invention,maybe provided .with anelectrical heating coil and thus the presentinvention may be used to provide cool airin warm.,,weather and .warm airin cool.

weather, at Willi Further and other objectswill be pointedout,

and. apparent in thereading. of the description hereinunder,particularly when takenin connectionwith the drawings in which Fig.1isan. elevationof an. embodiment of my invention shown partly insection, and Fig. 2 is a fragmentary sec.-

tion oftherotor employed taken along the. line,

A--BI'.

Referring ,toFig, 1,..l is a stand supporting an electric motor 2,having shaft extension 3 onto.

which isfixed a hub 41, carrying with it aradialflow air-impellerrotor,5.

Referring to. Fig.2, which is .a half section of therotor 5 taken alongthe line AB, Fig. 1,1ooking east. Fig. 2 is a section of the rotor perse,. without anyof. the .surroundingparts included,-

and is thus illustrated f0r.the sake ofclearness. The rotor 5 isnotnecessarily of a novel. structure, inso far as the radial air-flowblades are concernedjbut may be of any suitable conven-.

tional construction having end rings .6 and 'I, Fig. 1,..supportin'gintermediate blades such as 9 and I0, 'Figs.,1 and 2. The shape of theimpeller blades of. this rotor may have any suitable form,

but'for simplicity, are illustrated in the figure as'being radial,though they may advantageously have curved impelling surfaces.

Referring to'Fig. 1,. end ring 1 has made in- .tegrally with;it hub 4and said hub 4 is attached to ring! by means of spokes such as H, l2 andI3,'Fig.,2. These, spokes may be formed into a screw-type air-propeller,if and when, desired: and while a'screw-type propeller of such a smalldiameteris'not very effective in .producingradial,

air-flow, itdo'es'in effect and fact serve to reduce the resistance ofaxial air-flow which would otherwise be present if the said spokes wereformed 'difie'rently."

End ring fi, Fig. 1, maybe, a complete disk which serves to close theoutboard .end of the" rotor. 5, or the. outboard end ofv the rotor 5maybe of a ring; construction such as. illustrated, andsubstantiallyclosed by means of a lid l4. Lid l4 may have fixed to it anelectrical heating coil indicted by the dotted helices l5, which are sodisposed within the rotor 5 that a greater watt dissipation is obtainedfrom the said helices in that part of the rotor space having a greateramount of air intake. In other words, the heating coils are disposed insuch a way that the watt dissipation is proportional to the ability ofthe air currents to remove the heat from the region.

Referring to Fig. 1, an air deflecting surface H5 surrounds the rotor 5.The surface I6 is preferably formed by a surface revolution, being thatof a paraboloid or any other suitable surface which has a suitabledeflecting surface for the radial air currents from rotor 5. The surfaceit is supported by shell H which is provided with a hollow cylinder l8having a plurality of openings such as !9 and 20 to permit the influx offree air, indicated by the flow lines 2| and 22. Flow lines 2| and 22are indicated as not going through the set of openings l9 and 20, butthrough a set of openings generally at right angles thereto.

Flow lines 2| and 22 pass through the spokes which are formed into ascrew-type air-propeller, thence through the heating coil l5 and fromthere radially to a zone of the surface-of-revolution l6 from which theyare deflected, as indicated by following the lines of flow out into freeair. If the surface-of-revolution I6 is formed to be responsive to afocal point located generally about the center of the rotor 5, thedirection of the lines of flow into free air will diverge in the generaldirection of the dotted lines 23, or the sadi lines of flow will form apath generally parallel. in direction to the axis of the deflector, suchas indicated. by the flow lines 24, or the direction of flow may becaused to converge the general direction of the dotted lines 25, allaccording to the relative axial position of the rotor 5 with referenceto the focal point of the solid of revolution !5.

It will be appreciated that the flow lines 23, 24 and 25 referred to,really lie within air-flow cones or cylinders, as the air-flow is acolumn of air symmetrical about the axis of the rotor and deflector.

Hollow cylinder l8, Fig. 1, is provided with an internally threaded end26 which screws upon an externally threaded member 21, which saidexternal threaded member forms a part of the motor frame 2.

If the threads of 21 are cut right-handed, then a counter-clockwiserotation of the deflector member ll extends the said member in awesterly direction with reference to the center of rotator 5 and aclockwise rotation of member I! moves the said member in an oppositedirection, thus a rotary motion applied to member I'l functions tochange the position of the deflector with reference to general locationof the effective focal origin of the air-flow from the rotor 5, hence,changes the lines of air-flow to the general direction of 23, 24 or 25,as may be desired.

If warm air is desired instead of cool, the heating coils may be turnedon and the heat from the said coils focused into or diverged over thespace under heating and ventilation. Having these heating coils in thepath of air-flow permits a much larger wattage to be employed in thesecoils than would be permissible in still air with a simple reflector.

Such a construction has a high efficiency, lowmoment of inertia, bothfunctioning to reduce the size of motor 2, as Well as the attendant costof operation.

The focusing feature of the deflector serves to localize or spread outthe air-flow, eliminating the necessity of costly oscillatingaccessories common to screw-type propeller-ventilators.

The rotor, bein almost totally enclosed by solid material, makes itextremely diflicult to get into difficulty with extraneous objectscoming in contact with the rotor blades, such as so often takes placewith a screw-type propeller in a Wire guard.

An electrical heater employing a fan structure having a higher number ofsmall impeller blades for a given number of revolutions per minute, thana fan employing a small number of large blades for the same revolutionsper minute, operates more quietly than the latter. The experimentalbasis for this statement is found in an article by A. Page in TheProceedings of the Royal Society of Great Britain for 1925 entitled, Anexperimental study of the vibration in the blades and shaft of anairscrew (air-propeller).

The terminology used in this description and in the claims hereunder isemployed in conformity with standard practice turbine art.

Having described one embodiment of the invention, the scope thereof iscovered in the claims hereunder.

What I claim is:

1. In an electric device for heating free-air space, a driving motor, anair-impeller rotor having a cup-shaped form mounted axially upon anextended shaft of said motor and rotatable therewith, said rotor beingpositioned to intake air through the end thereof adjacent said motor, aconcave air-deflector radially surrounding said rotor, an intake port toadmit air to said rotor from behind said deflector and in front of saidmotor, an electrical heating unit positioned in the cavity of saidcup-shaped form, said deflector having its deflecting surface opendirectly to free-air space and formed to deflect heated exhaust air fromsaid rotor into direct stream lines to remotely disposed parts of saidspace.

2. In an electric device for heating free-air space. a driving motor, anair-impeller rotor having a cup-shaped form mounted axially upon anextended shaft of said motor and rotatable therewith, said rotor beingpositioned to intake air through the end thereof adjacent said motor,said rotor being provided with a number of impeller vanes in combinationwith a peripheral velocity thereof causing low operating noise, aconcave air-deflector radially surrounding said rotor, an intake port toadmit air to said rotor from behind said deflector and in front of saidmotor. an electrical heating unit positioned in the cavity of saidcup-shaped form, said deflector having its deflecting surface opendirectly to free-air space and formed to deflect heated exhaust air fromsaid rotor into direct stream lines to remotely disposed parts of saidspace.

3. In an electric device for heating free-air space, a driving motor, anair-impeller rotor having a cup-shaped form mounted axially upon anextended shaft of said motor and rotatable therewith, said rotor beingpositioned to intake air through the end thereof adjacent said motor,said rotor being provided with a relatively high number of relativelysmall impeller vanes operating at a peripheral velocity causingrelatively low operating noise, a concave air-deflector radiallysurrounding said rotor, an intake port to admit air to said rotor frombehind said deflector and in front of said motor, an electrical heatingunit positioned in the cavity of said cup-shaped form, said deflectorhaving its deflecting surface open directly to free-air space and formedto deflect heated exhaust air from said rotor into direct stream linesto remotely disposed parts of said space.

4. In an electric device for heating free-air space, a driving motor, arotor having air-impeller vanes arranged along a surface of revolutionand mounted axially upon an extended shaft of said motor and rotatabletherewith, said rotor being formed to intake air through the end thereofadjacent said motor, a concave air-deflector radially surrounding saidrotor, an intake air-port to admit air to said rotor from behind saiddeflector and in front of said motor, an electrical heating unit locatedin said surface of revolution, said deflector having its deflectingsurface open to free-air space, and said vanes formed to exhaust heatedair in a direction with respect to said surface to cause said air toassume direct stream lines to remotely disposed parts of said space.

5. In an electric device for heating free-air space, a driving motor, anair-impeller rotor having a cup-shaped form mounted axially upon anextended shaft of said motor with the open end of said cup-shaped formfacing said motor, said rotor being rotatable with said shaft, anelectrical heating unit located in the cavity of said cupshaped form toheat the rotor intake air, a concave air-deflector radially surroundingsaid rotor and mounted in moveable axial relation thereto, saiddeflector having its deflecting surface open directly to free-air spaceand deflecting exhaust air from said rotor into direct stream lines toremotely disposed parts of said space, the direction of saidstream-lines being fixed by said axial relation, and means adapted tochange said axial relation to cause a change in the direction of saidstream lines.

6. In an electric device for heating free-air space, a driving motor, anair-impeller rotor having a cup-shaped form mounted axially upon anextended shaft of said motor with the open end of said cup-shaped formfacing said motor, said rotor being rotatable with said shaft, anelectrical heating unit located in the cavity of said cupshaped form toheat the rotor intake air, a concave air-deflector radially surroundingsaid rotor and mounted in moveable axial relation thereto, saiddeflector having its deflecting surface open directly to free-air spaceand formed to converge the directions of exhaust air from said rotor atlocations in said space remotely disposed from said deflector, saidlocations being fixed by said axial relation, and means adapted tochange said axial relation to cause a change in the location of theconvergence of said directions.

7. In an electrically heated fan-heater, a driving motor, anair-impeller rotor mounted axially upon an extended shaft of said motor,said rotor having a coaxial free space internal of the impeller vanes ofsaid rotor, an electrical heating unit disposed in said space, a concaveair-deflector radially surrounding said rotor and formed to deflectradial exhaust air from said rotor away from said motor in a generallyaxial direction, and an intake air-port to admit air to said rotor fromspace between said rotor and said motor.

MONTFORD MORRISON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,366,519 Carmean et a1. Jan. 25,1921 1,627,229 Brown May 3, 1927 1,977,357 Slayback Oct. 16, 19342,131,484 Ringwald Sept. 27, 1938 2,334,501 Moeller Nov. 16, 1943

